RESOLVERTakes request from application, formats it intoUDP packet, sends to cache
CACHING NAMESERVERReturns the answer if already known,Otherwise searches for an authoritative serverwhich has the information.Caches the result for future queries.
AUTHORITATIVE NAMESERVERAn authoritative name server is a name server that gives answers in response to questions asked about names in a zone.An authoritative-only name server only returns answers to queries about domain names that have been specifically configured by the administrator.
Caching NameServers Where would you need them?Directly on a workstation or serverIn a Small Office / Home OfficeOn a corporate network
DNSCACHEdnscache maintains a limited-size cache of DNS information, 1 megabyte by default.Unlike BIND (which keeps growing), discards older cache entries.
PowerdnsLots of Backends:-MySQL, PostgreSQL, Oracle, DB2, OpenDBX,SQLite, BIND, LDAP, geo, pipe, etc.Install a Zone Editor :-PowerAdminWebDNSZoneAdminA webpage detailing its own stats.
BINDThe most widely used DNS software on the Internet.Widely documentedCan be used as a Caching nameserver